The present invention relates to an apparatus and method for calibrating earphones for audiometric testing, and more particularly to a system for separately calibrating audiometers to produce a normalized output and earphones according to an objective standard, so that any independently calibrated earphones may be used with any audiometer.
Audiometers are used to test the hearing capabilities of individuals. An audiometric test is performed by operating an audiometer to present precise audible tones or other stimulus to a test subject by acoustic transducers such as earphones. The test subject indicates whether the tones have been heard by an input mechanism such as a handswitch.
The earphones are typically either connected directly to the audiometer by use of industry standard stereo jacks or through the wall of a sound room by such stereo jacks connected to the audiometer. Earphones may include two wires and two stereo plugs, one for the each ear. A problem can arise if the two stereo plugs associated with the earphones are inserted into incorrect stereo jacks of the audiometer, for example if the left ear stereo plug is inserted into the right ear stereo jack of the audiometer. Extreme care is required to assure that earphones plugs are inserted properly into an audiometer before testing is conducted.
In addition, earphones traditionally are calibrated for a specific audiometer to which they are connected. That is, earphones can only be considered to be properly calibrated and ready for use if they are connected to the specific audiometer for which they had been calibrated. Earphones may not be used interchangeably with multiple audiometers. It is therefore very important to ensure that certain earphones are used with only certain audiometers so that valid audiometric test results are obtained.
The level of care that must be taken to assure that earphones are connected properly to an audiometer, and that earphones are only connected to a certain audiometer for which they are calibrated, requires significant administration and oversight. This increases the cost of operating and maintaining an audiometric testing facility. U.S. Pat. No. 6,468,224 describes a calibrated audiometer system that utilizes integrated circuit chips embedded in the plugs associated with the earphones and the handswitch, allowing identification information to be obtained to confirm that the headphones are being used with a correct audiometer and that the headphones are plugged into the proper jacks of the audiometer. It would be of further use in the art to provide an improved system and method for calibrating earphones for performing audiometric testing, so that any calibrated earphones may be used with any normalized audiometer.